Characterization and optimization of production of exopolysaccharide from Chlamydomonas reinhardtii

Chlamydomonas reinhardtii strain RAC was isolated based on its ability to secrete large amount of exopolysaccharide (EPS). The purified EPS had a molecular weight of 2.25 × 105 Da, and showed fibrillar structure with surfaces having sheet-like appearance. Chemical analysis showed the presence of galacturonic acid, ribose, arabinose, xylose, glucose, galactose and rhamnose sugars. The production of EPS was optimized by the classical one-at-a-time approach and Plackett–Burman design, followed by response surface methodology. The resulting response surface model was statistically significant (p < 0.5) and predicted maximum EPS production of 628 mg/L. The optimum production medium consisted of CaCl2 – 74, NaNO3 – 422, K2HPO4 – 10 and MgSO4 – 200 mg/L with a pH 7. The EPS showed significant antioxidant activity, which can have several industrial applications. This is the first report on characterization and production of EPS from a Chlamydomonas strain isolated from India. Its differences from the earlier reported EPS are discussed.

► EPS was purified from C. reinhardtii RAC, which was isolated from Palampur, India.
► The production of EPS was optimized using Plackett–Burman design and RSM.
► EPS had high molecular weight and sheet-like surfaces.
► GC–MS analysis showed that EPS was a heteropolysaccharide with 7 different sugars.
► EPS displayed strong antioxidant ability in vitro.